Critical to the evaluation of potential therapeufics (pharmacological, gene, or cell therapies) are sensitive and repeatable physiological assessments of muscle function applied to mouse models of dystrophy. Therefore, we are proposing to continue a research core that performs ex vivo, in situ, and whole animal assessments of muscle integrity and funcfion. This core will not only support the needs of the projects within the center, but will also serve as a nafional resource for performing funcfional evaluation of potenfial therapies for the muscular dystrophies. The Physiological Assessment Core resources are housed in the laboratory space designated to Dr. Barton, the Core Director. Dr. Barton is a muscle physiologist with extensive experience evaluating muscle function in mice. This includes all instrumentation for muscle physiological measurements, specialized equipment for hindlimb suspension experiments, documented free wheel running, and treadmill running, as well as interim storage of samples in both -8OC and liquid nitrogen freezers. We propose to extend our measures to include evaluation of whole animal respiratory funcfion, which will complement ex vivo assessment of the diaphragm. We believe that this Core has provided a previously unmet need in the past 5 years of its existence, and will confinue to be a valuable resource that will enable the enfire muscular dystrophy research community to ufilize these assays to assess the potential benefits of a large number of approaches to the treatment of different forms of muscular dystrophy.